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The phenomenon of plasticity in the striatum, and its relation with the striatum-nigra neuronal circuit has clinical and neurophysiological relevance to Parkinson and epilepsy. High frequency stimulation (HFS) can induce neural plasticity. Furthermore, it is possible to induce plasticity in the dorsal striatum and this can be modulated by substantia nigra activity. But it has not been shown yet what would be the effects in the striatum-nigra circuit after plasticity induction in striatum with HSF. Literature also misses a detailed description of the way back loop of the circuit: the striatal firing rate after substantia nigrás inhibition. We here conducted: First Experiment, application of HFS in dorsomedial striatum and measure of spontaneous and longlasting behavior expression in the open field three days later; Second, application of single pulses on dorsomedial striatum and measure of the evoked potentials in substantia nigra before and after HFS; Third Experiment: inhibition of substantia nigra and recording of the firing rate of dorsomedial striatum. HFS in dorsomedial striatum caused increased locomotion behaviors, but not classical stereotypy. However, rats had either an increase or decrease in substantia nigrás evoked potentials. Also, substantia nigrás inhibition caused an increase in dorsomedial striatum firing rate. Present data are suggestive of a potential application of HFS in striatum, as an attempt to modulate behavior rigidity and hypokinesia of diseases involving the basal ganglia, especially Parkinson´s Disease.

Background: Parkinson’s Disease (PD) exhibits the extrapyramidal symptoms caused due to the dopaminergic neuronal degeneration in the substantia nigra of the brain and depletion of Aldehyde Dehydrogenase (ALDH) enzyme. Objective: This study was designed to enlighten the importance of the Aldehyde dehydrogenase enzyme in protecting the dopamine levels in a living system. Camalexin, a potentially active compound, has been evaluated for its dopamine enhancing and aldehyde dehydrogenase protecting role in pesticide-induced Parkinson’s disease. Methods: AutoDock 4.2 software was employed to perform the docking simulations between the ligand camalexin and standard drugs Alda-1, Ropirinole with three proteins 4WJR, 3INL, 5AER. Consequently, the compound was evaluated for its in vivo neuroprotective role in the zebrafish model by attaining Institutional Animal Ethical Committee permission. The behavioral assessments and catecholamine analysis in zebrafish were performed. Results: The Autodock result shows that the ligand camalexin has a lower binding energy (-3.84) that indicates a higher affinity with the proteins when compared to the standard drug of proteins (-3.42). In the zebrafish model, behavioral studies provided evidence that camalexin helps in the improvement of motor functions and cognition. The catecholamine assay has proved that there is an enhancement in dopamine levels, as well as an improvement in aldehyde dehydrogenase enzyme. Conclusion: The novel compound, camalexin, offers a protective role in Parkinson’s disease model by its interaction with neurochemical proteins and also in alternative in vivo model.

Neurodegenerative disease, for instance, Parkinson’s disease (PD), is associated with substantia nigra dopaminergic neuronal loss with subsequent striatal dopamine reduction, leading to motor deficits. Currently, there is no available effective therapy for PD; thus, novel therapeutic agents such as natural antioxidants with neuroprotective effects are emerging. Alpha-mangostin (αM) is a xanthone derivative compound from mangosteen peel with a cytoprotective effect depicted in neurodegenerative disease models. However, αM has low aqueous solubility and low biodistribution in the brain. Nanostructured lipid carriers (NLC) have been used to encapsulate bioactive compounds delivered to target organs to improve the oral bioavailability and effectiveness. This study aimed to investigate the effect of αM and αM encapsulated in NLC (αM-NLC) in mice with rotenone-induced PD-like neurodegeneration. Forty male ICR mice were divided into normal, PD, PD+αM, and PD+ αM-NLC groups. Vehicle, αM (25 mg/kg/48 h), and αM-NLC (25 mg/kg/48 h) were orally administered, along with PD induction by intraperitoneal injection of rotenone (2.5 mg/kg/48 h) for 4 consecutive weeks. Motor abilities were assessed once a week using rotarod and hanging wire tests. Biochemical analysis of brain oxidative status was conducted, and neuronal populations in substantia nigra par compacta (SNc), striatum, and motor cortex were evaluated using Nissl staining. Tyrosine hydroxylase (TH) immunostaining of SNc and striatum was also evaluated. Results showed that rotenone significantly induced motor deficits concurrent with significant SNc, striatum, and motor cortex neuronal reduction and significantly decreased TH intensity in SNc (p < 0.05). The significant reduction of brain superoxide dismutase activity (p < 0.05) was also detected. Administrations of αM and αM-NLC significantly reduced motor deficits, prevented the reduction of TH intensity in SNc and striatum, and prevented the reduction of neurons in SNc (p < 0.05). Only αM-NLC significantly prevented the reduction of neurons in both striatum and motor cortex (p < 0.05). These were found concurrent with significantly reduced malondialdehyde level and increased catalase and superoxide dismutase activities (p < 0.05). Therefore, this study depicted the neuroprotective effect of αM and αM-NLC against rotenone-induced PD-like neurodegeneration in mice. We indicated an involvement of NLC, emphasizing the protective effect of αM against oxidative stress. Moreover, αM-NLC exhibited broad protection against rotenone-induced neurodegeneration that was not limited to nigrostriatal structures and emphasized the benefit of NLC in enhancing αM neuroprotective effects.

Background and aim This study investigated the effect of Kava extract (Piper methysticum), a medicinal plant that has been worldly used by its anxiolytic effects, on monoamine oxidase (MAO) activity of mice brain after 21 days of treatment as well as anxiolytic and locomotor behavior. Furthermore, the in vitro inhibitory profile of Kava extract on MAO-B activity of mouse brain was evaluated. Experimental procedure Mice were treated with Kava extract (10, 40, 100 and 400 mg/kg) for 21 days by gavage. After behavioral analysis (plus maze test and open field), MAO activity in different mouse brain structures (cortex, hippocampus, region containing the substantia nigra and striatum) were performed. MAO-B inhibitory profile was characterized in vitro. Results The treatment with Kava extract (40 mg/kg) increased the percentage of entries of mice into the open arms. Ex vivo analysis showed an inhibition on MAO-B activity caused by Kava extract in cortex (10 mg/kg) and in the region containing the substantia nigra (10 and 100 mg/kg). In vitro, Kava extract also reversibly inhibited MAO-B activity with IC50 = 14.62 μg/mL and, increased Km values at the concentrations of 10 and 30 μg/mL and decreased Vmax value at 100 μg/mL. Conclusion Kava extract showed different effects on MAO-B isoform depending on the brain structure evaluated. Therefore, the use of Kava extract could be promissory in pathologies where MAO-B is the pharmacological target.

HOXA transcript at the distal tip (HOTTIP), a newly identified long noncoding RNA, has been shown to exhibit anti-inflammatory effects and inhibit oxygen-glucose deprivation-induced neuronal apoptosis. However, its role in Parkinson's disease (PD) remains unclear. 1-Methyl-4-phenylpyridium (MPP+) and 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP) were used to establish PD models in SH-SY5Y and BV2 cells and in C57BL/6 male mice, respectively. In vitro, after HOTTIP knockdown by sh-HOTTIP transfection, HOTTIP and FOXO1 overexpression promoted SH-SY5Y apoptosis, BV2 microglial activation, proinflammatory cytokine expression, and nuclear factor kappa-B and NACHT, LRR and PYD domains-containing protein 3 inflammasome activation. Overexpression of miR-615-3p inhibited MPP+-induced neuronal apoptosis and microglial inflammation and ameliorated HOTTIP- and FOXO1-mediated nerve injury and inflammation. In vivo, HOTTIP knockdown alleviated motor dysfunction in PD mice and reduced neuronal apoptosis and microglial activation in the substantia nigra. These findings suggest that inhibition of HOTTIP mitigates neuronal apoptosis and microglial activation in PD models by modulating miR-615-3p/FOXO1. This study was approved by the Ethics Review Committee of the Affiliated Hospital of Qingdao University, China (approval No. UDX-2018-042) in June 2018.

Parkinson’s disease, the second most prevalent neurodegenerative disorder worldwide, is characterized by a progressive loss of dopaminergic neurons in substantia nigra pars compacta, causing motor symptoms. This disorder’s main hallmark is the formation of intraneuronal protein inclusions, named Lewy bodies and neurites. The major component of these arrangements is α-synuclein, an intrinsically disordered and soluble protein that, in pathological conditions, can form toxic and cell-to-cell transmissible amyloid structures. Preventing α-synuclein aggregation has attracted significant effort in the search for a disease-modifying therapy for Parkinson’s disease. Small molecules like SynuClean-D, epigallocatechin gallate, trodusquemine, or anle138b exemplify this therapeutic potential. Here, we describe a subset of compounds containing a single aromatic ring, like dopamine, ZPDm, gallic acid, or entacapone, which act as molecular chaperones against α-synuclein aggregation. The simplicity of their structures contrasts with the complexity of the aggregation process, yet the block efficiently α-synuclein assembly into amyloid fibrils, in many cases, redirecting the reaction towards the formation of non-toxic off-pathway oligomers. Moreover, some of these compounds can disentangle mature α-synuclein amyloid fibrils. Their simple structures allow structure-activity relationship analysis to elucidate the role of different functional groups in the inhibition of α-synuclein aggregation and fibril dismantling, making them informative lead scaffolds for the rational development of efficient drugs.

G-Protein coupled D2 autoreceptors expressed on dopamine neurons (D2Rs) inhibit transmitter release and cell firing at axonal endings and somatodendritic compartments. Mechanistic details of somatodendritic dopamine release remain unresolved, partly due to insufficient information on the subcellular distribution of D2Rs. Previous studies localizing D2Rs have been hindered by a dearth of antibodies validated for specificity in D2R knockout animals and have been limited by the small sampling areas imaged by electron microscopy. This study utilized sub-diffraction fluorescence microscopy and electron microscopy to examine D2 receptors in a superecliptic pHlourin GFP (SEP) epitope tagged D2 receptor knockin mouse. Incubating live slices with an anti-SEP antibody achieved the selective labeling of plasma membrane associated receptors for immunofluorescent imaging over a large area of the substantia nigra pars compacta (SNc). SEP-D2Rs appeared as puncta-like structures along the surface of dendrites and soma of dopamine neurons visualized by antibodies to tyrosine hydroxylase (TH). TH-associated SEP-D2Rs displayed a cell surface density of 0.66 puncta per μm(2), which corresponds to an average frequency of 1 punctum every 1.50 μm. Separate ultrastructural experiments using silver-enhanced immunogold revealed that membrane-bound particles represented 28% of total D2Rs in putative dopamine cells within the SNc. Structures immediately adjacent to dendritic membrane gold particles were unmyelinated axons or axon varicosities (40%), astrocytes (19%), other dendrites (7%), or profiles unidentified (34%) in single sections. Some apposed profiles also expressed D2Rs. Fluorescent and ultrastructural analyses also provided the first visualization of membrane-D2Rs at the axon initial segment, a compartment critical for action potential generation. The punctate appearance of anti-SEP staining indicates there is a population of D2Rs organized in discrete signaling sites along the plasma membrane, and for the first time a quantitative estimate of spatial frequency is provided.

Thymoquinone (TQ) is one of the leading phytochemicals, which is abundantly found in Nigella sativa L. seeds. TQ exhibited various biological effects such as antioxidant, anti-inflammatory, antimicrobial, and anti-tumoral in several pre-clinical studies. Parkinson's disease (PD) is a long-term neurodegenerative disease with movement difficulties, and the common feature of neurodegeneration in PD patients is caused by dopaminergic neural damage in the substantia nigra pars compacta. The neuroprotective activity of TQ has been studied in various neurological disorders. TQ-mediated neuroprotection against PD is yet to be reported in a single frame; therefore, this review is intended to narrate the potentiality of TQ in the therapy of PD. TQ has been shown to protect against neurotoxins via amelioration of neuroinflammation, oxidative stress, and apoptosis, thereby protecting neurodegeneration in PD models. TQ could be an emerging therapeutic intervention in PD management, but mechanistic studies remain to be investigated to clarify its neuroprotective role.

Levodopa is a cornerstone in Parkinson’s disease treatment. Beneficial effects are mainly by binding on D2 receptors. Docking simulations of a set of compounds including well-known D2-ligands and a pool of Boron-Containing Compounds (BCC), particularly boroxazolidones with a tri/tetra-coordinated boron atom, were performed on the D2 Dopamine receptor (D2DR). Theoretical results yielded higher affinity of the compound DPBX, a Dopaboroxazolidone, than levodopa on D2DR. Essential interactions with residues in the third and sixth transmembrane domains of the D2DR appear to be crucial to induce and stabilize interactions in the active receptor state. Results from a motor performance evaluation of a murine model of Parkinson’s disease agree with theoretical results, as DPBX showed similar efficacy to that of levodopa for diminishing MPTP-induced parkinsonism. This beneficial effect was disrupted with prior Risperidone (D2DR antagonist) administration, supporting the role of D2DR in the biological effect of DPBX. In addition, DPBX limited neuronal loss in substantia nigra in a similar manner to that of levodopa administration.

Parkinson disease (PD) prevalence varies by ethnicity. In an earlier study, we replicated the reduced vulnerability to PD in an admixed population, using 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP)-susceptible C57BL/6 J, MPTP-resistant CD-1 and their F1 crossbreds. In the present study, we investigated if the differences have a developmental origin. Substantia nigra was evaluated at postnatal days 2 (P2), P6, P10, P14, P18, and P22. C57BL/6 J mice had smaller nigra and fewer dopaminergic neurons than the CD-1 and crossbreds at P2, which persisted through development. A significant increase in numbers and nigral volume was observed across strains until P14. A drastic decline thereafter was specific to C57BL/6 J. CD-1 and crossbreds retained their numbers from P14 to stabilize with supernumerary neurons at adulthood. The neuronal size increased gradually to attain adult morphology at P10 in the resistant strains, vis-a-vis at P22 in C57BL/6 J. Accordingly, in comparison to C57BL/6 J, the nigra of CD-1 and reciprocal crossbreds possessed cytomorphological features of resilience, since birth. The considerably lesser dopaminergic neuronal loss in the CD-1 and crossbreds was seen at P2 and P14 and thereafter was complemented by attenuated developmental cell death. The differences in programmed cell death were confirmed by reduced TUNEL labelling, AIF, and caspase-3 expression. GDNF expression aligned with the cell death pattern at P2 and P14 in both nigra and striatum. Earlier maturity of nigra and its neurons appears to be better features that reflect as MPTP resistance at adulthood. Thus, variable MPTP vulnerability in mice and also differential susceptibility to PD in humans may arise early during nigral development.

Background Prolonged inflammation, oxidative stress, and protein aggregation are important factors contributing to Parkinson’s disease (PD) pathology. A known ROS generator, pesticide paraquat (PQ), was indicated as an environmental substance potentially increasing the incidence of PD and is used to model this disease. We investigated if a combination of inflammation and oxidative stress in subthreshold doses would exacerbate the modelled neuropathology. Methods We examined the late effects of acute or repeated peripheral inflammation induced by low dose of LPS (10 μg/kg, ip) on PQ toxicity in the rat nigrostriatal dopaminergic pathway, microglial activation markers and expression of major Lewy bodies proteins, α-synuclein and synphilin-1. Results We observed that LPS increased, while PQ decreased body temperature and microglia CD11b expression in the SN. Single LPS pretreatment, 3 h before repeated weekly PQ injections (4×) slightly aggravated neuronal degeneration in the SN. Moreover, degeneration of dopaminergic neurons after weekly repeated inflammation itself (4×) was observed. Interestingly, repeated LPS administration combined with each PQ dose counteracted such effect. The expression of α-synuclein decreased after repeated LPS injections, while only combined, repeated LPS and PQ treatment lowered the levels of synphilin-1. Therefore, α-synuclein and synphilin-1 expression change was influenced by different mechanisms. Concomitantly, decreased levels of the two proteins correlated with decreased degeneration of dopaminergic neurons and with a normalized microglia activation marker. Conclusions Our results indicate that both oxidative insult triggered by PQ and inflammation caused by peripheral LPS injection can individually induce neurotoxicity. Those factors act through different mechanisms that are not additive and not selective towards dopaminergic neurons, probably implying microglia. Repeated, but small insults from oxidative stress and inflammation when administered in significant time intervals can counteract each other and even act protective as a preconditioning effect. The timing of such repetitive insults is also of essence.

Parkinson's disease (PD) is a neurodegenerative disorder that affects over 10 million aging people worldwide. This condition is characterized by the degeneration of dopaminergic neurons in the pars compacta region of the substantia nigra (SNpc) and by aggregation of proteins, commonly α-synuclein (SNCA). The formation of Lewy bodies that encapsulate aggregated proteins in lipid vesicles is a hallmark of PD. Glycosylation of proteins and neuroinflammation are involved in the pathogenesis. SNCA has many posttranslational modifications and interacts with components of membranes that affect aggregation. The large membrane lipid dolichol accumulates in the brain upon age and has a significant effect on membrane structure. The replacement of dopamine and dopaminergic neurons are at the forefront of therapeutic development. This review examines the role of membrane lipids, glycolipids, glycoproteins and dopamine in the aggregation of SNCA and development of PD. We discuss the SNCA-dopamine-neuromelanin-dolichol axis and the role of membranes in neuronal stem cells that could be a regenerative therapy for PD patients.

Mild to moderate dopaminergic (DA) neuronal death in substantia nigra pars compacta (SNc) as the main pathological hallmark of Parkinson's disease (PD) is usually silent and does not produce marked clinical symptoms. In this study, we investigated the association between SNc DA neuronal loss and serum levels of total bilirubin (TB), selenium (Se), and zinc (Zn) in 6-hydroxydopamine (6-OHDA) animal model of PD. The neurotoxin of 6-OHDA was injected into the medial forebrain bundle of right hemisphere by stereotaxic surgery. Two conventional behavioral tests were carried out in several steps after the toxin to confirm the model reproduction and quantify severity and progress of 6-OHDA-induced PD. Blood samples were collected within 1 week before the toxin and in the second, fifth, and eighth weeks thereafter. Immunohistochemistry (IHC) assessments were performed on the rat's brain to determine the severity of DA neuronal loss in SNc. The severity of behavioral symptoms and TB levels were progressively increased in 6-OHDA-treated rats. On the other hand, Se and Zn levels in them were lower than control. These changes were observed in rats with severe or mild behavioral symptoms. Also, IHC revealed that changes in TB, Se, and Zn associate with SNc DA neuronal loss but do not correlate with its severity. Significant changes in serum levels of TB, Se, and Zn in the mild SNc DA neuronal loss suggest them as valuable parameters for establishment of a serum profile for early detection of PD.

Parkinson’s disease is a common neurodegenerative disease affecting the movement and well-being of most elderly. The manifestations of Parkinson’s disease often include resting tremor, stiffness, bradykinesia, and muscular rigidity. The typical hallmark of Parkinson’s disease is the destruction of neurons in the substantia nigra and the presence of Lewy bodies in different compartments of the central nervous system. Due to various limitations to the currently available treatments, immunotherapies have emerged to be the new approach to Parkinson’s disease treatment. This approach shows some positive outcomes on the efficacy by removing the aggregated species of alpha-synuclein, which is believed to be one of the causes of Parkinson’s disease. In this review, an overview of how alpha-synuclein contributes to Parkinson’s disease and the effects of a few new immunotherapeutic treatments, including BIIB054 (cinpanemab), MEDI1341, AFFITOPE, and PRX002 (prasinezumab) that are currently under clinical development, will be discussed.

Alpha-synuclein aggregation and mitochondrial dysfunction are main pathological hallmarks of Parkinson's disease (PD) and several other neurodegenerative diseases, collectively known as synucleinopathies. However, increasing evidence suggests that they may not be sufficient to cause PD. Here we propose the role of hypoxia as a missing link that connects the complex interplay between alpha-synuclein biochemistry and pathology, mitochondrial dysfunctions and neurodegeneration in PD. We review the partly conflicting literature on alpha-synuclein binding to membranes and mitochondria and its impact on mitochondrial functions. From there, we focus on adverse changes in cellular environments, revolving around hypoxic stress, that may trigger or facilitate PD progression. Inter-dependent structural re-arrangements of mitochondrial membranes, including increased cytoplasmic exposure of mitochondrial cardiolipins and changes in alpha-synuclein localization and conformation are discussed consequences of such conditions. Enhancing cellular resilience could be an integral part of future combination-based therapies of PD. This may be achieved by boosting the capacity of cellular and specifically mitochondrial processes to regulate and adapt to altered proteostasis, redox, and inflammatory conditions and by inducing protective molecular and tissue re-modelling. (c) 2021 The Author(s). Published by Elsevier Inc. This is an open access article under the CC BY-NC-ND license ( http://creativecommons.org/licenses/by-nc-nd/4.0/ )

Although the etiology of Parkinson's disease (PD) is poorly understood, studies in animal models revealed loss of dopamine and the dopaminergic neurons harbouring the neurotransmitter to be the principal cause behind this neuro-motor disorder. Neuroinflammation with glial cell activation is suggested to play a significant role in dopaminergic neurodegeneration. Several biomolecules have been reported to confer dopaminergic neuroprotection in different animal models of PD, owing to their anti-inflammatory potentials. Garcinol is a tri-isoprenylated benzophenone isolated from Garcinia sp. and accumulating evidences suggest that this molecule could provide neuroprotection by modulating oxidative stress and inflammation. However, direct evidence of dopaminergic neuroprotection by garcinol in the pre-clinical model of PD is not yet reported. The present study aims to investigate whether administration of garcinol in the MPTP mouse model of PD may ameliorate the cardinal motor behavioural deficits and prevent the loss of dopaminergic neurons. As expected, garcinol blocked the parkinsonian motor behavioural deficits which include akinesia, catalepsy, and rearing anomalies in the mice model. Most importantly, the degeneration of dopaminergic cell bodies in the substantia nigra region was significantly prevented by garcinol. Furthermore, garcinol reduced the inflammatory marker, glial fibrillary acidic protein, in the substantia nigra region. Since glial hyperactivation-mediated inflammation is inevitably associated with the loss of dopaminergic neurons, our study suggests the anti-inflammatory role of garcinol in facilitating dopaminergic neuroprotection in PD mice. Hence, in the light of the present study, it is suggested that garcinol is an effective anti-parkinsonian agent to block motor behavioural deficits and dopaminergic neurodegeneration in PD.

© The Author(s) 2021., In Parkinson’s disease, the dysfunction of the dopaminergic nigrostriatal tract involves the loss of function of dopaminergic neurons of the substantia nigra pars compacta followed by death of these neurons. The functional recovery of these neurons requires a deep knowledge of the molecules that maintain the dopaminergic phenotype during adulthood and the mechanisms that subvert their activity. Previous studies have shown that transcription factor NURR1, involved in differentiation and maintenance of the dopaminergic phenotype, is downregulated by α-synuclein (α-SYN). In this study, we provide a mechanistic explanation to this finding by connecting α-SYN-induced activation of glycogen synthase kinase-3 (GSK-3) with NURR1 phosphorylation followed by proteasomal degradation. The use of sequential deletion mutants and single point mutants of NURR1 allowed the identification of a domain comprising amino acids 123-PSSPPTPSTPS-134 that is targeted by GSK-3 and leads to subsequent ubiquitination and proteasome degradation. This study provides a detailed analysis of the regulation of NURR1 stability by phosphorylation in synucleinopathies such as Parkinson’s disease., This study was funded by the Spanish Ministry of Economy and Competitiveness (MINECO) (grant PID2019-110061RB-I00 for A.C and PID2019-105600RB-I00 for I.L.B.) and The Autonomous Community of Madrid (grant B2017/ BMD-3827 for A.C. and B2017/BMD-3813 for I.L.B.).

Background Changes in dopaminergic neural function can be induced by an acute inflammatory state that, by altering the integrity of the neurovasculature, induces neuronal stress, cell death and causes functional deficits. Effectively blocking these effects of inflammation could, therefore, reduce both neuronal and functional decline. To test this hypothesis, we inhibited vascular adhesion protein 1 (VAP-1), a membrane-bound protein expressed on the endothelial cell surface, that mediates leukocyte extravasation and induces oxidative stress. Method We induced dopaminergic neuronal loss by infusing lipopolysaccharide (LPS) directly into the substantia nigra (SN) in rats and administered the VAP-1 inhibitor, PXS-4681A, daily. Results LPS produced: an acute inflammatory response, the loss of dopaminergic neurons in the SN, reduced the dopaminergic projection to SN target regions, particularly the dorsolateral striatum (DLS), and a deficit in habit learning, a key function of the DLS. In an attempt to protect SN neurons from this inflammatory response we found that VAP-1 inhibition not only reduced neutrophil infiltration in the SN and striatum, but also reduced the associated striatal microglia and astrocyte response. We found VAP-1 inhibition protected dopamine neurons in the SN, their projections to the striatum and promoted the functional recovery of habit learning. Thus, we reversed the loss of habitual actions, a function usually dependent on dopamine release in DLS and sensitive to striatal dysfunction. Conclusions We establish, therefore, that VAP-1 inhibition has an anti-inflammatory profile that may be beneficial in the treatment of dopamine neuron dysfunction caused by an acute inflammatory state in the brain.

Parkinson’s disease and related synucleinopathies are characterized by the abnormal accumulation of alpha-synuclein aggregates, loss of dopaminergic neurons, and gliosis of the substantia nigra. Although clinical evidence and in vitro studies indicate disruption of the Blood-Brain Barrier in Parkinson’s disease, the mechanisms mediating the endothelial dysfunction is not well understood. Here we leveraged the Organs-on-Chips technology to develop a human Brain-Chip representative of the substantia nigra area of the brain containing dopaminergic neurons, astrocytes, microglia, pericytes, and microvascular brain endothelial cells, cultured under fluid flow. Our αSyn fibril-induced model was capable of reproducing several key aspects of Parkinson’s disease, including accumulation of phosphorylated αSyn (pSer129-αSyn), mitochondrial impairment, neuroinflammation, and compromised barrier function. This model may enable research into the dynamics of cell-cell interactions in human synucleinopathies and serve as a testing platform for target identification and validation of novel therapeutics.

Целью данной работы являлась оценка выживаемости популяции зрелых дофаминергических (ДА-ергических) нейронов чёрной субстанции двух альфа-синуклеин нокаутных линий мышей Abel-KO и ΔFlox-KO, а также бессинуклеиновых животных abg-КО в условиях МФТП-токсического моделирования паркинсонического синдрома. Методы исследования: Водный раствор нейротоксина МФТП вводили 3-месячным мышам внутрибрюшинно в дозе 30 мг/кг ежедневно в течение 5 дней по субхроническому протоколу. Через 21 день после последней инъекции МФТП у животных извлекали головной мозг, фиксировали в холодном растворе Карнуа и парафинизировали для последующего приготовления гистологических препаратов на ротационном микротоме Leica RM2265 (Leica Biosystems, Германия). Иммуногистохимическое окрашивание проводили антителами против тирозингидроксилазы (моноклональные антитела мыши, Sigma, разведение 1:2000). Сравнительный морфометрический анализ популяции ДА-ергических нейронов чёрной субстанции выполнен с учётом поправки Аберкромби. Результаты: Установлено, что в условиях дефицита альфа-синуклеина мыши устойчивы к потере ДА-ергических нейронов в компактной части ЧС после введения МФТП. При генетической делеции всех трёх синуклеинов чувствительность ДА-ергических нейронов ЧС к токсическому действию МФТП не отличается от таковой у животных с немодифицированным геномом. Заключение. На основании проведённого морфометрического анализа предполагается, что особенности чувствительности к нейротоксину МФТП у альфа-синуклеин нокаутных линий мышей обусловлены повышением функциональной активности (замещением) бета-синуклеина, оптимизирующего захват ДА синаптическими везикулами. The aim of this study was to assess survival of mature dopaminergic (DAergic) neuronal population in the substantia nigra pars compacta (SNpc) of two alpha-synuclein knockout mice strains (Abel-KO and ΔFlox-KO) and of non-synuclein animals (abg-KO) in MPTP-induced parkinsonism. Material and methods: MPTP water solution was administered to 3-month-old mice intraperitoneally (30 mg/kg daily for 5 days) according to a subchronic protocol. On the 21st day after the last MPTP injection, the brain was excised, fixed in cold Carnoy’s solution and paraffined for the subsequent preparation of histological samples on a Leica RM2265 rotary microtome (Leica Biosystems, Germany). Immunohistochemical staining was performed with antibodies against tyrosine hydroxylase (mouse monoclonal antibodies, Sigma, dilution 1:2000). A comparative morphometric analysis of substantia nigra dopaminergic neurons was performed using the Abercrombie correction. Results: MPTP-treated alpha-synuclein deficient mice were resistant to the loss of DAergic neurons in the SNpc. Genetic deletion of all three synucleins restored the sensitivity of SNpc DAergic neurons to the MPTP toxicity, which did not differ from the sensitivity of wild type animals. Conclusion: Based on the morphometric analysis, it was assumed that the specific features of MPTP sensitivity in alpha-synuclein knockout mice are due to an increased functional activity (substitution) of beta-synuclein, which optimizes the capture of DA by synaptic vesicles.

Motoric disturbances in Parkinson’s disease (PD) derive from the loss of dopaminergic neurons in the substantia nigra. Intestinal dysfunctions often appear long before manifestation of neuronal symptoms, suggesting a strong correlation between gut and brain in PD. Oxidative stress is a key player in neurodegeneration causing neuronal cell death. Using natural antioxidative flavonoids like Rutin, might provide intervening strategies to improve PD pathogenesis. To explore the potential effects of micro (mRutin) compared to nano Rutin (nRutin) upon the brain and the gut during PD, its neuroprotective effects were assessed using an in vitro PD model. Our results demonstrated that Rutin inhibited the neurotoxicity induced by A53T α-synuclein (Syn) administration by decreasing oxidized lipids and increasing cell viability in both, mesencephalic and enteric cells. For enteric cells, neurite outgrowth, number of synaptic vesicles, and tyrosine hydroxylase positive cells were significantly reduced when treated with Syn. This could be reversed by the addition of Rutin. nRutin revealed a more pronounced result in all experiments. In conclusion, our study shows that Rutin, especially the nanocrystals, are promising natural compounds to protect neurons from cell death and oxidative stress during PD. Early intake of Rutin may provide a realizable option to prevent or slow PD pathogenesis.

Background and purpose Modafinil is a potent eugeroic (wakefulness-promoting) drug that is prescribed to treat narcolepsy and has a low incidence of abuse. Although previous studies have shown that modafinil-induced arousal depends on the dopamine receptors and transporters, the specific part/s of the dopamine transmitter system underlying this mechanism remained unclear. Here, we investigated the role of mesencephalic dopamine neurons in modafinil-evoked arousal. Experimental approach A dopamine indicator (dLight1.1) was employed to detect dopamine changes in the nucleus accumbens (NAc) and dorsal striatum. We specifically lesioned mesencephalic dopamine neurons via diphtheria toxin (DTA) in the dopamine transporter (DAT)-Cre mice. Then, the sleep-wake states were recorded to evaluate the effect of modafinil on arousal. Finally, the extent of DTA-induced lesions was determined by immunohistochemistry. Key results Modafinil promptly increased dopamine levels in the NAc and dorsal striatum in a dose-dependent manner. Lesioning of dopamine neurons in the substantia nigra pars compacta (SNc) or ventral tegmental area (VTA) had no significant effects on physiological sleep-wake cycles. Modafinil at 90 mg·kg-1 increased continuous wakefulness for 355 min in control mice. However, these effects were slightly decreased by 6.7% in the SNc-lesioned mice and were prominently diminished by 32.8% in VTA-lesioned mice. Furthermore, the modafinil-induced arousal was completely blocked in the SNc-VTA-lesioned mice, whereas lesions of the dorsal raphe nucleus had no effect. Conclusion and implications Taken together, our findings indicate that mesencephalic dopamine neurons are essential for modafinil-induced arousal.

Previous studies reveal that hydrogen sulphide (H2 S) exerts neuroprotection against neurotoxin-induced Parkinson's disease (PD), but the underlying mechanism remains elusive. The present study was aimed to investigate whether H2 S inhibits neuronal apoptosis of substantia nigra with the involvement of autophagy via promoting leptin signalling in 6-hydroxydopamine (6-OHDA)-induced PD rats. In this study, neuronal apoptosis was analysed by TUNEL staining, the activity of caspase-3 was measured by Caspase-3 fluorometric assay kit, the expressions of Bax, Bcl-2, Beclin-1, LC3II, P62 and leptin were determined by Western blot analysis, and the numbers of autophagosomes and autolysosomes were assessed by transmission electron microscopy. Results showed that NaHS, a donor of exogenous H2 S, mitigates 6-OHDA-induced the increases in the numbers of TUNEL-positive cells, the activity of caspase-3 and the expression of Bax, and attenuates 6-OHDA-induced a decrease in the expression of Bcl-2 in substantia nigra of rats. In addition, 6-OHDA enhanced the expressions of Beclin-1, LC3-II and P62, increased the number of autophagosomes, and decreased the number of autolysosomes in the substantia nigra, which were also blocked by administration of NaHS. Furthermore, NaHS reversed 6-OHDA-induced the down-regulation of leptin expression in the substantia nigra, and treatment with leptin-OBR, a blocking antibody of leptin receptor, attenuated the inhibition of NaHS on neuronal apoptosis and the improvement of NaHS on the blocked autophagic flux in substantia nigra of 6-OHDA-treated rats. Taken together, these results demonstrated that H2 S attenuates neuronal apoptosis of substantia nigra depending on restoring impaired autophagic flux through up-regulating leptin signalling in PD.

Extracellular vesicles (EVs) shed by neurons and glia in the central nervous system carry a cargo of specific bioactive molecules, facilitating intercellular communication. However, in neurodegenerative disease conditions, EVs carry pathological miRNAs and/or proteins involved in spreading the disease. Such EVs are also found in the cerebrospinal fluid (CSF) or the circulating blood, the characterization of which could identify biomarkers linked to specific neurodegenerative diseases. Moreover, EVs secreted by various stem/progenitor cells carry therapeutic miRNAs and proteins, which have shown promise to alleviate symptoms and slow down the progression of neurodegenerative diseases. The ability of exogenously administered EVs to easily cross the blood-brain barrier with no risk for thrombosis and incorporate into neurons and glia has also opened up the possibility of using nano-sized EVs as carriers of therapeutic drugs or bioactive proteins. This review summarizes the role and function of EVs in alpha-synuclein-mediated neurodegeneration and the spread of alpha-synuclein from neurons to glia, leading to the activation of the inflammatory response in Parkinson's disease (PD). Moreover, the promise of brain-derived EVs in the CSF and the circulating blood for biomarker discovery and the efficacy of stem/progenitor cell-derived EVs or EVs loaded with bioactive molecules such as dopamine, catalase, curcumin, and siRNAs, in alleviating Parkinsonian symptoms are discussed.

Abnormal accumulation of α-synuclein contributes to the formation of Lewy bodies in the substantia nigra, which is considered the typical pathological hallmark of Parkinson’s disease. Recent research indicates that angiotensin-(1–7) plays a crucial role in several neurodegenerative disorders, including Parkinson’s disease, but the underlying mechanisms remain elusive. In this study, we used intraperitoneal administration of rotenone to male Sprague-Dawley rats for 4 weeks to establish a Parkinson’s disease model. We investigated whether angiotensin-(1–7) is neuroprotective in this model by continuous administration of angiotensin-(1–7) into the right substantia nigra for 4 weeks. We found that angiotensin-(1–7) infusion relieved characteristic parkinsonian behaviors and reduced α-synuclein aggregation in the substantia nigra. Primary dopaminergic neurons were extracted from newborn Sprague-Dawley rat substantia nigras and treated with rotenone, angiotensin-(1–7), and/or the Mas receptor blocker A-779 for 24 hours. After binding to the Mas receptor, angiotensin-(1–7) attenuated apoptosis and α-synuclein aggregation in rotenone-treated cells. Primary dopaminergic neurons were also treated with angiotensin-(1–7) and/or the autophagy inhibitor 3-methyladenine for 24 hours. Angiotensin-(1–7) increased α-synuclein removal and increased the autophagy of rotenone-treated cells. We conclude that angiotensin-(1–7) reduces α-synuclein aggregation by alleviating autophagy dysfunction in Parkinson’s disease. Therefore, the angiotensin-(1–7)/Mas receptor axis plays an important role in the pathogenesis of Parkinson’s disease and angiotensin-(1–7) has potential therapeutic value for Parkinson’s disease. All experiments were approved by the Biological Research Ethics Committee of Nanjing First Hospital (approval No. DWSY-2000932) in January 2020.

Treadmill exercise has been recognized as an effectively therapeutic strategy for Parkinson's disease (PD). However, its exact molecular mechanism of promoting PD remain unclear. Recently, the NLRP3 inflammasome is considered to play a critical role in the pathogenesis of PD. In this study, we investigated whether NLRP3 inflammasome was involved in treadmill exercise-induced neuroprotection and anti-inflammation effect in the 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP) model of PD. 8-week-old male mice (C57BL/6 strain) were divided into four groups: Control, MPTP, MPTP + EX and EX. MPTP was intraperitoneally injected into mice to establish chronic PD model. The open-field test and pole test were used to assess motor function. The results showed that treadmill exercise significantly alleviated motor dysfunction and dopaminergic neuron degeneration induced by MPTP. In addition, we also found that treadmill exercise suppressed MPTP-triggered microglia activation and the co-localization of NLRP3+/Iba-1+ cells in the substantia nigra. These effects were associated with suppression NLRP3 inflammasome via down-regulation of TLR4/MyD88/NF-κB pathway. Overall, our study demonstrated that treadmill exercise could effectively alleviates neuronal damage via inhibition of NLRP3 inflammasome and microglial activation in MPTP-induced PD mouse model.

Parkinson’s disease (PD) pathology involves progressive degeneration and death of vulnerable dopamine neurons in the substantia nigra. Extensive axonal arborization and distinct functions make this type of neurons particularly sensitive to homeostatic perturbations, such as protein misfolding and Ca2+ dysregulation. Endoplasmic reticulum (ER) is a cell compartment orchestrating protein synthesis and folding, as well as synthesis of lipids and maintenance of Ca2+ homeostasis in eukaryotic cells. When misfolded proteins start to accumulate in ER lumen the unfolded protein response (UPR) is activated. UPR is an adaptive signaling machinery aimed at relieving of protein folding load in the ER. When UPR is chronic, it can either boost neurodegeneration and apoptosis or cause neuronal dysfunctions. We have recently discovered that mesencephalic astrocyte-derived neurotrophic factor (MANF) exerts its prosurvival action in dopamine neurons and in an animal model of PD through the direct binding to UPR sensor inositol-requiring protein 1 alpha (IRE1α) and attenuation of UPR. In line with this, UPR targeting resulted in neuroprotection and neurorestoration in various preclinical animal models of PD. Therefore, growth factors (GFs), possessing both neurorestorative activity and restoration of protein folding capacity are attractive as drug candidates for PD treatment especially their blood-brain barrier penetrating analogs and small molecule mimetics. In this review, we discuss ER stress as a therapeutic target to treat PD; we summarize the existing preclinical data on the regulation of ER stress for PD treatment. In addition, we point out the crucial aspects for successful clinical translation of UPR-regulating GFs and new prospective in GFs-based treatments of PD, focusing on ER stress regulation.

Introduction Parkinson's disease (PD) is a neurodegenerative disease characterized by the deposition of disease-associated α-synuclein, which is thought to follow a sequential distribution in the human brain. Accordingly, α-Synuclein pathology affects the substantia nigra (SN) only in Braak stage 3 out of 6. Moreover, intracellular accumulation of α-synuclein follows maturation from non-ubiquitinated (p62 negative) to ubiquitinated (p62 positive) forms (Lewy bodies). Mitochondrial dysfunction is thought to be a central player in the pathogenesis of PD. It is not clear whether the nigral neurons already show mitochondrial alterations in stages preceding the deposition of α-synuclein in the SN, and how deposition of pre-aggregates or ubiquitinated mature inclusions relate to this. Methods Using cell-based morphometric immunohistochemistry we evaluated the volume density of mitochondrial complex-IV (COX-IV) immunoreactivity in SN neurons lacking or showing α-synuclein deposits in non-diseased individuals and those with Lewy body pathology Braak stage 3 with prominent nigral α-synuclein deposition. Results Increased volume density of COX-IV immunoreactivity appears before detectable pathological α-synuclein in nigral neurons. The volume density decreases significantly as pathological pre-aggregates of α-synuclein accumulates in the neurons and remains at a low level in neurons with p62 positive Lewy bodies. Conclusions COX-IV expression shows a change before and during accumulation of α-synuclein in the SN underpinning the role of early mitochondrio protective therapy strategies in PD.

Nicotine exerts its reinforcing actions by activating nicotinic acetylcholine receptors (nAChRs), but the detailed mechanisms remain unclear. Nicotine releases 3, 4-dihydroxyphenylalanine (DOPA), a neurotransmitter candidate in the central nervous system. Here, we investigated the distribution of GPR143, a receptor of DOPA, and nAChR subunits in the nigrostriatal and mesolimbic regions. We found GPR143 mRNA-positive cells in the striatum and nucleus accumbens. Some of them were surrounded by tyrosine hydroxylase (TH)-immunoreactive fibers. There were some GPR143 mRNA-positive cells coexpressing TH, and nAChR subunit α4 or α7 in the substantia nigra and ventral tegmental area. These findings suggest that DOPA-GPR143 signaling may be involved in the nicotine action in the nigrostriatal and mesolimbic dopaminergic systems.

Parkinson’s disease (PD) is a severe neurodegenerative disease characterized by classic motor features associated with the loss of dopaminergic neurons and appearance of Lewy bodies in the substantia nigra. Due to the complexity of PD, a definitive diagnosis in the early stages and effective management of symptoms in later stages are difficult to achieve in clinical practice. Previous research has shown that colocalization of A2A receptors (A2AR) and dopamine D2 receptors (D2R) may induce an antagonistic interaction between adenosine and dopamine. Clinical trials have found that the A2AR antagonist istradefylline decreases dyskinesia in PD and could be used as an adjuvant to levodopa treatment. Meanwhile, the incretin hormone glucagon-like peptide 1 (GLP1) mainly facilitates glucose homeostasis and insulin signaling. Preclinical experiments and clinical trials of GLP1 receptor (GLP1R) agonists show that they may be effective in alleviating neuroinflammation and sustaining cellular functions in the central nervous system of patients with PD. In this review, we summarize up-to-date findings on the usefulness of A2AR antagonists and GLP1R agonists in PD management. We explain the molecular mechanisms of these medications and their interactions with other neurotransmitter receptors. Furthermore, we discuss the efficacy and limitations of A2AR antagonists and GLP1R agonists in clinical practice.

Parkinson’s disease (PD) is a movement disorder associated with severe loss of mainly dopaminergic neurons in the substantia nigra. Pathological hallmarks include Lewy bodies, and loss of neuromelanin, due to degeneration of neuromelanin-containing dopaminergic neurons. Despite being described over 200 years ago, the etiology of PD remains unknown. Here, we highlight the roles of reactive oxygen species (ROS), iron, alpha synuclein (α-syn) and neuromelanin in a toxic feedback loop culminating in neuronal death and spread of the disease. Dopaminergic neurons are particularly vulnerable due to decreased antioxidant concentration with aging, constant exposure to ROS and presence of neurotoxic compounds (e.g. ortho-quinones). ROS and iron increase each other’s levels, creating a state of oxidative stress. α-Syn aggregation is influenced by ROS and iron but also increases ROS and iron via its induced mitochondrial dysfunction and ferric-reductase activity. Neuromelanin’s binding affinity is affected by increased ROS and iron. Furthermore, during neuronal death, neuromelanin is degraded in the extracellular space, releasing its bound toxins. This cycle of events continues to neighboring neurons in the form of a toxic loop, causing PD pathology. The increase in ROS and iron may be an important target for therapies to disrupt this toxic loop, and therefore diets rich in certain ‘nutraceuticals’ may be beneficial. Turmeric is an attractive candidate, as it is known to have anti-oxidant and iron chelating properties. More studies are needed to test this theory and if validated, this would be a step towards development of lifestyle-based therapeutic modalities to complement existing PD treatments.

Background: Depression has a high prevalence and high mortality and a tremendous negative impact on people’s quality of life. This study was considered to examine the effect of levodopa and spironolactone (SPIR) in 6-hydroxydopamine (6-OHDA)-induced depression-like behavior. Methods: Parkinson was induced by the unilateral intra-nigral injection of 6-OHDA (8 µg/2 µL/rat) in the central region of the substantia nigra pars compacta (SNc). In the levodopa treatment group, 21 days after the injection of 6-OHDA, the rats were treated with (i.p.) injections of levodopa (15 mg/kg) for 14 consecutive days. In the other group, only SPIR (25 mg/kg) was added to levodopa (15 mg/kg) as a concurrent therapy according to the treatment protocol. Anxiety and depression-like behavior were assessed by behavioral tests such as passive avoidance task (PAT), open field test (OFT), tail suspension test (TST), and forced swimming test (FST). Results: Intra-nigral injection of 6-OHDA in the SNc increased anxiety and depression-like behavior. Our results showed that the use of levodopa (15 mg/kg) treatment significantly attenuated depression-like behavior induced by 6-OHDA in FST (P

Bombyx batryticatus, the dried larvae of Bombyx mori infected by Beauveria bassiana, is a renowned traditional medicine. Previous report shows that B. batryticatus improved behavioral impairments, protected dopaminergic neurons, and maintained dopamine levels by inhibiting oxidative signaling in murine Parkinson’s disease model. In this study, the inhibitory effects of B. batryticatus on 1-methyl 4-phenyl 1,2,3,6-tetrahydropyridine (MPTP)-induced Parkinson’s disease in mice was investigated and explored the corresponding molecular mechanisms, while focusing on NF-κB signaling. Consequently, it was found that B. batryticatus inhibited glial and microglial activation and the levels of neuroinflammatory mediators, such as Cox-2, iNOS, and NF-kB, in the substantia nigra pars compacta. Moreover, pre-inhibition of NF-κB by BAY 11-7082, a κB kinase inhibitor, could neutralize the inhibitory effects of B. batryticatus against the activation of glia and microglia formerly induced by MPTP. It can be considered that B. batryticatus holds implications in providing anti-inflammatory neuroprotection by regulating NF-κB signaling.

Gut microbiota is closely related to the Parkinson's disease (PD) pathogenesis. Additionally, aggregation of α-synuclein (α-syn) is central to PD pathogenesis. Here we identified the further mechanisms of gut microbiota in PD. A mouse model with PD was established via injection of MPTP. Normal or MPTP-induced PD like animals were treated with FMT from healthy normal mice. Pole test and traction test were performed to examine the effects of FMT on motor function of PD mice. Fecal SCFAs were assessed by gas chromatography-mass spectrometry. The α-syn level in the substantia nigra pars compacta (SN) of mice was measured using western blot. Dopaminergic neurons and microglial activation in the SN were analyzed by immunohistochemistry (IHC) and immunofluorescence (IF) staining. FMT alleviated physical impairment, decreased fecal SCFAs in a mouse model of PD. Additionally, FMT decreased the expression of α-syn, as well as inhibited the activation of microglia in the SN, and blocked the TLR4/PI3K/AKT/NF-κB signaling in the SN and striatum. FMT could protect mice against PD via suppressing α-syn expression and inactivating the TLR4/PI3K/AKT/NF-κB signaling.

Analytical chemistry 93(32), 11108 - 11115 (2021). doi:10.1021/acs.analchem.1c01128, Studies of the metal content of metalloproteins in tissues from the human central nervous system (CNS) can be compromised by preparative techniques which alter levels of, or interactions between, metals and the protein of interest within a complex mixture. We developed a methodological workflow combining size exclusion chromatography, native isoelectric focusing, and either proton or synchrotron X-ray fluorescence within electrophoresis gels to analyze the endogenous metal content of copper-zinc superoxide dismutase (SOD1) purified from minimal amounts (, Published by American Chemical Society, Columbus, Ohio

Background: Parkinson’s disease (PD) is a progressive neurological disorder where loss of dopamine neurons in the substantia nigra and dopamine depletion in the striatum cause characteristic motor symptoms. Currently, no treatment is able to halt the progression of PD. Glial cell line-derived neurotrophic factor (GDNF) rescues degenerating dopamine neurons both in vitro and in animal models of PD. When tested in PD patients, however, the outcomes from intracranial GDNF infusion paradigms have been inconclusive, mainly due to poor pharmacokinetic properties. Objective: We have developed drug-like small molecules, named BT compounds that activate signaling through GDNF’s receptor, the transmembrane receptor tyrosine kinase RET, both in vitro and in vivo and are able to penetrate through the blood-brain barrier. Here we evaluated the properties of BT44, a second generation RET agonist, in immortalized cells, dopamine neurons and rat 6-hydroxydopamine model of PD. Methods: We used biochemical, immunohistochemical and behavioral methods to evaluate the effects of BT44 on dopamine system in vitro and in vivo. Results: BT44 selectively activated RET and intracellular pro-survival AKT and MAPK signaling pathways in immortalized cells. In primary midbrain dopamine neurons cultured in serum-deprived conditions, BT44 promoted the survival of the neurons derived from wild-type, but not from RET knockout mice. BT44 also protected cultured wild-type dopamine neurons from MPP+-induced toxicity. In a rat 6-hydroxydopamine model of PD, BT44 reduced motor imbalance and seemed to protect dopaminergic fibers in the striatum. Conclusion: BT44 holds potential for further development into a novel, possibly disease-modifying, therapy for PD.

Ultrasound mediated neuromodulation has been demonstrated to a safe treatment strategy in the field of neuroscience. In this study, low-intensity pulsed ultrasound (LIPUS) was used to treat Parkinson's disease (PD) models induced by 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP) and 1-methyl-4-phenylpyridinium (MPP+) to explore the possibility of ultrasound neuroprotective effect on PD. The results demonstrated that LIPUS treatment can attenuate the central neurotoxicity of MPTP in mice, reduce the loss of tyrosine hydroxylase positive neurons in the substantia nigra pars compacta and decrease the apoptosis in the section of substantia nigra. The movement and balance dysfunctions in PD mice were improved with LIPUS treatment. In addition, we demonstrated that LIPUS can inhibit the decreased activity and increased apoptosis of dopaminergic neurons induced by MPP+, restrain the accumulation of reactive oxygen species (ROS) and decrease of mitochondrial membrane potential caused by MPP+. Moreover, LIPUS stimulation alone did not cause any cytotoxicity and tissue damage in our study. Taken together, the protective and regulatory effects of LIPUS on dopaminergic neurons make it possible as a new, safe and noninvasive treatment for PD.

Parkinson's disease (PD) and diabetes mellitus share similar pathophysiological characteristics, genetic and environmental factors. It has been reported that people with diabetes mellitus appear to have a remarkable higher incidence of PD than age matched non diabetic individuals. Evidences suggest that use of antidiabetic glitazone is associated with a diminished risk of PD incidence in patients with diabetes. This study examined the effect of lobeglitazone, a member of thiazolidinedione class, in rat model of Parkinson's disease with diabetes co-morbidity. Rats received either rotenone and/or a combination of streptozocin and a high calorie diet for disease induction and they were treated with different doses of lobeglitazone or its vehicle. Behavioral tests comprising rotarod, bar test and rearing test were conducted to evaluate the motor function. Changes in the level tyrosine hydroxylase, TNF-α and NF-κB were analyzed using ELISA. In the same brain regions the possible changes in PPAR-γ receptor level were evaluated. Findings showed that although lobeglitazone tends to reverse the effect of rotenone in animals with diabetes, it was just able to prevent partly the motor defect in rearing test. Furthermore, lobeglitazone (1 mg/kg) reversed, in substantia nigra and striatum, the changes in tyrosine hydroxylase, TNF-α, NF-κB and PPAR-γ receptor content induced by rotenone in rats with diabetic condition. Although other preclinical studies are needed, these findings suggest that lobeglitazone is a promising neuroprotective candidate for clinical trials for PD patients with diabetes co-morbidity.

Parkinson's disease (PD), the typical neurodegenerative disease, is characterized by the progressive loss of dopaminergic neurons in the substantia nigra (SN). However, no therapeutic agent used currently could slow down neuronal cell loss so as to decelerate or halt the progression of PD. Traditional Chinese medicine (TCM) has been utilized to treat the dysfunction of the autonomic nervous system. Wen-Shen-Yang-Gan decoction (WSYGD) has a good effect on the clinical treatment of PD with constipation. However, it is not clear which ingredients and what mechanism are responsible for the therapeutic effect. In this study, the pharmacodynamic study of WSYGD in PD mice was applied. Concurrently, a novel method for the identification of metabolic profiles of WSYGD has been developed. Finally, we found that WSYGD could protect the PD mice induced by rotenone. The underlying mechanism of the protective effect may be related to the reduction of the DA neurons apoptosis via reducing inflammatory reaction. By virtue of UPLC-MS and chemoinformatics method, 35 prototype compounds and 27 metabolites were filtered out and tentatively characterized. In conclusion, this study provides an insight into the metabolism of WSYGD in vivo to enable understanding of the metabolic process and therapeutic mechanism of PD.

Background Alpha-synuclein (α-syn) preformed fibril (PFF)-induced pathology can be used to study the features and progression of synucleinopathies, such as Parkinson's disease. Intrastriatal injection of mouse α-syn PFFs produce accumulation of α-syn pathology in both mice and rats. Previous studies in mice have revealed that greater sequence homology between the α-syn amino acid sequence used to produce PFFs with that of the endogenous host α-syn increases α-syn pathology in vivo. New methods Based on the prediction that greater sequence homology will result in more α-syn pathology, PFFs generated from recombinant rat α-syn (rPFFs) were used instead of PFFs produced from recombinant mouse α-syn (mPFFs), which are normally used in the model. Rats received unilateral intrastriatal injections of either rPFFs or mPFFs and accumulation of α-syn phosphorylated at serine 129 (pSyn) was examined at 1-month post-surgery. Results Rats injected with mPFFs exhibited abundant accumulation of α-syn inclusions in the substantia nigra and cortical regions, whereas in rats injected with rPFFs had significantly fewer SNpc neurons containing pSyn inclusions (≈60% fewer) and little, if any, pSyn inclusions were observed in the cortex. Conclusions Our results suggest that additional factors beyond the degree of sequence homology between host α-syn and injected recombinant α-syn impact efficiency of seeding and subsequent inclusion formation. More practically, these findings caution against the use of rPFFs in the rat preformed fibril model.

Autophagy in dopamine (DA) neurons is concerned to be associated with Parkinson's disease (PD), but the detailed mechanism remains unknown. Herein, we aimed to investigate the function of microRNA (miR)-29c-3p in autophagy in PD models. Intraperitoneal injection of MPTP (20 mg/kg) was given to C57BL/6 mice to establish PD mouse model. SH-SY5Y cells were treated with MPP+ (1 mmol/L) to establish in vitro PD model. The results indicated that in the substantia nigra pars compacta (SNpc) DA neurons of PD mice, autophagy was activated accompanied by down-regulated miR-29c-3p and up-regulated ten-eleven translocation 2 (TET2) expression. Up-regulation of miR-29c-3p inhibited TET2 expression and SNpc (including DA neurons) autophagy in PD mice. In vitro PD model confirmed that MPP+ treatment markedly down-regulated miR-29c-3p expression and up-regulated TET2 expression in SH-SY5Y cells in a dose/time-dependent manner. Moreover, miR-29c-3p up-regulation also inhibited autophagy and TET2 expression in vitro. Additionally, TET2 was proved to be targeted and down-regulated by miR-29c-3p. TET2 knockdown inhibited MPP+ -induced autophagy, whereas TET2 over-expression reversed the effects of miR-29c-3p over-expression on SH-SY5Y cell autophagy. Overall, miR-29c-3p over-expression inhibits autophagy in PD models, which may be mediated by TET2. Our finding may provide new insights for regulating autophagy to improve PD progression.

Encompassing live cell imaging and morphometrics at the microscopical level, we showed here, for the first time, protection of neuronal-like cells by the novel drug candidate, SKIP, against the Parkinson's disease-related neurotoxin, rotenone. Mechanistically, rotenone disrupted microtubule dynamics, which SKIP partially repaired through microtubule end-binding proteins, coupled with increasing neurite branch length. Given the previous association of rotenone toxicity with increased dopaminergic cell death hallmarking Parkinson's disease, we chose an established rat model of 6-hydroxydopamine (6-OHDA) toxicity to initially evaluate SKIP in vivo. SKIP pretreatment showed protection against nigral dopaminergic cell degeneration and improved motor behavior in the forelimb asymmetry test. With Parkinson's disease being a major neurodegenerative disorder, afflicting millions of people globally, and with disease modification challenges, SKIP may hold promise for future therapeutic development.

Activation of cannabinoid 1 receptors (CB1 R) modulates multiple behaviours, including exploration, motor coordination and response to psychostimulants. It is known that CB1 R expressed by either excitatory or inhibitory neurons mediates different behavioural responses to CB1 R activation, yet the involvement of CB1 R expressed by medium spiny neurons (MSNs), the neuronal subpopulation that expresses the highest level of CB1 R in the CNS, remains unknown. We report a new genetically modified mouse line that expresses functional CB1 R in MSN on a CB1 R knockout (KO) background (CB1 R(MSN) mice). The absence of cannabimimetic responses measured in CB1 R KO mice was not rescued in CB1 R(MSN) mice, nor was decreased spontaneous locomotion, impaired instrumental behaviour or reduced amphetamine-triggered hyperlocomotion measured in CB1 R KO mice. Significantly, reduced novel environment exploration of an open field and absence of amphetamine sensitization (AS) measured in CB1 R KO mice were fully rescued in CB1 R(MSN) mice. Impaired motor coordination in CB1 R KO mice measured on the Rotarod was partially rescued in CB1 R(MSN) mice. Thus, CB1 R expressed by MSN control exploration, motor coordination, and AS. Our study demonstrates a new functional roles for cell specific CB1 R expression and their causal link in the control of specific behaviors.

Parkinson’s disease (PD) is a progressive nervous system disorder and its pathological hallmark is the presence of fibrillar aggregates called Lewy bodies (LB) in substantia nigra. As it is also well established, [Formula: see text]-synuclein is the major constituent of the LB. Although numerous experimental studies have been conducted on inhibition of [Formula: see text]-synuclein aggregation, the detailed inhibitory mechanism is not still fully elucidated. In this paper, we first focused on identifying the binding modes of nicotine and dopamine to [Formula: see text]-synuclein using molecular docking. Then, we performed comparative molecular dynamics (MD) simulations to enlighten the inhibition mechanism of [Formula: see text]-synuclein for both dopamine and nicotine. MD simulations demonstrate that both nicotine and dopamine stabilize dominant helical structure of [Formula: see text]-synuclein and so they inhibit their conformational transitions. Moreover, the favorable and unfavorable contribution residues, which play a key role in the inhibition of [Formula: see text]-synuclein, were determined using MM-PBSA analysis. The findings in this study will shed light on understanding the inhibition mechanism of [Formula: see text]-synuclein and guide potential drug development studies of degenerative diseases.

Parkinson’s disease (PD), one of the most common neurodegenerative disorders, is characterized by progressive neurodegeneration of dopaminergic (DA) neurons in the substantia nigra pars compacta (SNpc). DJ-1 acts essential roles in neuronal protection and anti-neuroinflammatory response, and its loss of function is tightly associated with a familial recessive form of PD. However, the molecular mechanism of DJ-1 involved in neuroinflammation is largely unclear. Here, we found that wild-type DJ-1, rather than the pathogenic L166P mutant DJ-1, directly binds to the subunit p65 of nuclear factor-κB (NF-κB) in the cytoplasm, and loss of DJ-1 promotes p65 nuclear translocation by facilitating the dissociation between p65 and NF-κB inhibitor α (IκBα). DJ-1 knockout (DJ-1−/−) mice exhibit more microglial activation compared with wild-type littermate controls, especially in response to lipopolysaccharide (LPS) treatment. In cellular models, knockdown of DJ-1 significantly upregulates the gene expression and increases the release of LPS-treated inflammatory cytokines in primary microglia and BV2 cells. Furthermore, DJ-1 deficiency in microglia significantly enhances the neuronal toxicity in response to LPS stimulus. In addition, pharmacological blockage of NF-κB nuclear translocation by SN-50 prevents microglial activation and alleviates the damage of DA neurons induced by microglial DJ-1 deficiency in vivo and in vitro. Thus, our data illustrate a novel mechanism by which DJ-1 facilitates the interaction between IκBα and p65 by binding to p65 in microglia, and thus repressing microglial activation and exhibiting the protection of DA neurons from neuroinflammation-mediated injury in PD.

Therapeutic options for Parkinson's disease (PD) are limited to a symptomatic approach, making it a global threat. Targeting aggregated alpha-synuclein (α-syn) clearance is a gold standard for ameliorating PD pathology, bringing autophagy into the limelight. Expression of autophagy related genes are under the regulation by histone modifications, however, its relevance in PD is yet to be established. Here, preformed fibrillar form (PFF) of α-syn was used to induce PD in wistar rats, which were thereafter subjected to treatment with trehalose (tre, 4g/kg, orally), a potent autophagy inducer and sodium butyrate (SB, 300 mg/kg, orally), a pan histone deacetylase inhibitor alone as well as in combination. The combination treatment significantly reduced motor deficits as evidenced after rotarod, narrow beam walk, and open field tests. Novel object location and recognition tests were performed to govern cognitive abnormality associated with advanced stage PD, which was overcome by the combination treatment. Additionally, with the combination, the level of pro-inflammatory cytokines were significantly reduced, along with elevated levels of dopamine and histone H3 acetylation. Further, mRNA analysis revealed that levels of certain autophagy related genes and proteins implicated in PD pathogenesis significantly improved after administration of both tre and SB. Immunofluorescence and H&E staining in the substantia nigra region mirrored a potential improvement after treatment with both tre and SB. Therefore, outcomes of the present study were adequate to prove that combinatorial efficacy with tre and SB may prove to be a formidable insight into ameliorating PD exacerbated by PFF α-syn as compared to its individual efficacy.

Some cardiovascular symptoms in the early stage of Parkinson's disease (PD) were related to degeneration of the rostral ventrolateral medulla (RVLM) catecholaminergic neurons. To date, little is known about the effects of hydrogen water on early stage of PD. Here, protective actions of hydrogen-saturated saline (HS) on rotenone-induced PD rats, as well as its underlying mechanisms were investigated. HS was used to treat PD rats at three general stages; early, medium and late, which were represented by rotenone induced rats for 0, 7 and 14 days. HS treatment significantly alleviated the cardiovascular and motor symptoms in rotenone-induced PD rats, improved the survival number of RVLM catecholaminergic neurons and nigral dopamine neurons only in early and medium stages of PD rats. Decreased levels of reactive oxygen species (ROS) and alpha-synuclein (α-Syn), transformation of microtubule associated protein 1 light chain 3 (LC3)-I/II and degradation of sequestosome 1 (p62) were detected, as well as increased expression level of autophagy related protein 5 (ATG5) and B-cell lymphoma-2 interacting protein 1 (Beclin-1) in the RVLM and substantia nigra (SN) after HS treatment in early and medium stages of PD rats. In addition, phosphorylation levels of phosphatidylinositol-3-kinase (PI3K), protein kinase B (Akt) and mammalian rapamycin target protein (mTOR) decreased after HS treatment in early and medium stages of PD rats. The results suggested that HS treatment exerted beneficial effects in early and medium stages before motor impairments emerged but not in the late stage of rotenone-induced PD rats. It exerted neuroprotection with RVLM catecholaminergic neurons and nigral dopamine neurons, mediated in part by decreasing levels of ROS and α-Syn through increasing autophagy machinery which were partly via inhibiting PI3K-Akt-mTOR pathway.

Parkinson's disease (PD) is the most prevalent neurodegenerative motor disorder. While PD has been attributed to dopaminergic neuronal death in substantia nigra pars compacta (SNpc), accumulating lines of evidence have suggested that reactive astrogliosis is critically involved in PD pathology. These pathological changes are associated with α-synuclein aggregation, which is more prone to be induced by an A53T mutation. Therefore, the overexpression of A53T-mutated α-synuclein (A53T-α-syn) has been utilized as a popular animal model of PD. However, this animal model only shows marginal-to-moderate extents of reactive astrogliosis and astrocytic α-synuclein accumulation, while these phenomena are prominent in human PD brains. Here we show that Adeno-GFAP-GFP virus injection into SNpc causes severe reactive astrogliosis and exacerbates the A53T- α-syn-mediated PD pathology. In particular, we demonstrate that AAV-CMV-A53T-α-syn injection, when combined with Adeno-GFAP-GFP, causes more significant loss of dopaminergic neuronal tyrosine hydroxylase level and gain of astrocytic GFAP and GABA levels. Moreover, the combination of AAV-CMV-A53T-α-syn and Adeno-GFAP-GFP causes an extensive astrocytic α-syn expression, just as in human PD brains. These results are in marked contrast to previous reports that AAV-CMV-A53T-α-syn alone causes α-syn expression mostly in neurons but rarely in astrocytes. Furthermore, the combination causes a severe PD-like motor dysfunction as assessed by rotarod and cylinder tests within three weeks from the virus injection, whereas Adeno-GFAP-GFP alone or AAV-CMV-A53T-α-syn alone does not. Our findings implicate that inducing reactive astrogliosis exacerbates PD-like pathologies and propose the virus combination as an advanced strategy for developing a new animal model of PD.